Is penetration power the property of radiation or of the material and on what factors does the penetration of electromagnetic radiation depend?
MOHAMMED ABDUL SHAKOOR
Hyderabad
Radiation is energy transmitted through space in the form of electromagnetic waves or energetic particles. Various radiations are alpha particle radiation, beta particle radiation, neutrons, gamma rays, x-rays etc. All the radiations have low to very high energy carried with them so as to enable them to travel long distances and penetrate obstruction if any coming in their path.
In the process of penetration, it removes electrons from atoms in materials through which it passes. This process is called ionization, and the high frequency electromagnetic waves and energetic particles that can produce ionizations are known as ionizing radiations. Non-ionizing radiations are not energetic enough to ionize atoms and interact with materials in ways that create different hazards than ionizing radiation. Examples of non-ionizing radiation include visible light, low energy microwaves, radio and TV waves and ultra violet light.
Alpha particles (consisting of two neutrons and two protons ejected from the nucleus of an atom) are charged and relatively heavy and they interact intensely with atoms in materials they encounter, giving up their energy over a very short range. In air, their travel distances are limited to no more than a few centimetres. Alpha particles are easily shielded against and can be stopped by a single sheet of paper.
Beta particles (electrons emitted from the nucleus of a radioactive atom) are much less massive and less charged and interact less intensely with atoms in the materials they pass through, which give them a longer range than alpha particles. Thin layers of metal or plastic stop beta particles.
A gamma ray (a packet or photon of electromagnetic radiation emitted from the nucleus during radioactive decay and occasionally accompanying the emission of an alpha or beta particle) are of much higher energy. Gamma rays have no mass or charge and interact less intensively with matter than ionizing particles.
Because gamma radiation loses energy slowly, gamma rays are able to travel significant distances. Depending upon their initial energy, gamma rays can travel tens or hundreds of meters in air. An X –ray behaves similarly to Gamma rays. Thus it can seen that penetration would depend basically on the energy level and mass of the radiation particles/waves and also on the materials (number of electrons which can be removed from the atoms) property.
S.P.S JAIN
Former Member, Engineering, Indian Railways
Greater Noida, Uttar Pradesh
This week’s question
Why do we have a burning sensation in our finger when we cut green chilly? Which ingredient of the green chilly causes it and is it harmful?
Dalpat Singh Rathore, Jaipur
